1. Field of the Invention
The invention relates in general to a chip module and a fabricating method thereof, and more particularly to a chip module with a power amplifier and a fabricating method thereof.
2. Description of the Related Art
How to increase the portability of electronic communication devices is an important trend for the industry of wireless communication, and is also essential to increase product competiveness. The size and weight of electronic communication devices must be reduced in order to increase the portability of electronic communication devices. An electronic communication device s normally has a substrate and the chip is assembled on the substrate by a packaging technology. Thus, the size of the chip package structure directly affects the size of the whole of an electronic product.
FIG. 1 is a perspective view illustrating a typical wireless module 10. Referring to FIG. 1, the wireless module 10 has a substrate 11, at least one chip packaging structure 12, a power amplifier chip 13, and many passive units 14 such as resistors, inductances and capacitors. The passive units 14 are assembled on the substrate 11 by surface mount technology (SMT).
Currently, the power amplifier chip 13 usually applies a IIVV semiconductor chip such as gallium arsenide (GaAs) chip for providing a high frequency signal. Because the power amplifier chip 13 is usually used in a strict high frequency environment, the flip-chip technology or wireless chip level (WLCSP) package is unsuitable for assembling the chip 13 on the substrate 11. In general, the power amplifier chip is adhered to the substrate 11, and wires are used for electrically connecting the power amplifier chip with the substrate 11. Then, the power amplifier chip is buried in a packaging material. Further, the wires must be buried in a packaging material for avoiding the exposed wires causing an antenna to excite energy.
FIGS. 2A and 2B are respectively a cross-sectional view and top view illustrating the package structure of a typical power amplifier chip. Referring to FIGS. 2A and 2B, a dam structure 160 encircling the power amplifier chip 120 is formed on the substrate 110. The space encircled by the dam structure 160 with the packaging material 170 for encircling the power amplifier chip 120 and the wires 130 and for providing the power amplifier chip 120 and the wires 130 with necessary insulation protection. The above package structure is capable of appropriately packaging the power amplifier chip 120 in the wireless module 10. However, during manufacturing the dam structure 160, a predetermined space on the substrate 110 must be reserved for manufacturing the dam structure 160. Therefore, the dam structure 160 will certainly increase the size of the package structure and jeopardize the portability of electronic devices.
Thus, the invention provides a chip module and a fabricating method thereof capable of appropriately packaging the power amplifier chip 120 in the chip module and avoiding unnecessary increase in the size of the package structure.